Fix NPE in outline view

Occassionally the outline view caused problems, when the integrity file was not well-formed.

That is if the object which is normally displayed was not present, it may have caused a NPE thrown from the outline view. This fix explicitly checks for those cases and handles them more gracefully.

The especially annoying case was when entering a constant in a suite. If you have stopped typing after "constant" without specifying a name yet, the integrity file is not valid, however the outline will already parse it and will crash (dialog with NPE pops up) because of the missing constant name.